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. 2019 Mar 19;12(1):114.
doi: 10.1186/s13071-019-3345-7.

Impact of 19 years of mass drug administration with ivermectin on epilepsy burden in a hyperendemic onchocerciasis area in Cameroon

Charlotte Boullé  1   2 , Alfred K Njamnshi  3   4   5 , Fidèle Dema  6 , Michel K Mengnjo  3 , Joseph Nelson Siewe Fodjo  7   8 , Anne-Cécile Zoung-Kanyi Bissek  4   9   10 , Patrick Suykerbuyk  8 , Cédric G Lenou-Nanga  11 , Hugues C Nana-Djeunga  11 , Joseph Kamgno  4   11 , Cédric B Chesnais  1 , Michel Boussinesq  1 , Robert Colebunders  12
Affiliations

Impact of 19 years of mass drug administration with ivermectin on epilepsy burden in a hyperendemic onchocerciasis area in Cameroon

Charlotte Boullé et al. Parasit Vectors. .

Abstract

Background: Surveys conducted in 1991-1992 in the Mbam Valley (Cameroon) revealed that onchocerciasis was highly endemic, with community microfilarial loads (CMFL) > 100 microfilariae/snip in some villages. Also in 1991-1992, a survey of suspected cases of epilepsy (SCE) found 746 SCE using a questionnaire administered to individuals identified by key informants, with prevalences reaching 13.6% in some communities. From 1998, annual community-directed treatment with ivermectin (CDTI) was implemented to control onchocerciasis. In 2017, a door-to-door household survey was conducted in three of the villages visited in 1991-1992, using a standardized 5-item epilepsy screening questionnaire.

Results: In 2017, a total of 2286 individuals living in 324 households were screened (582 in Bayomen, 553 in Ngongol and 1151 in Nyamongo) and 112 SCE were identified (4.9%). Neurologists examined 92 of these SCE and confirmed the diagnosis of epilepsy for 81 of them (3.5%). Between the surveys in 1991-1992 and 2017, the prevalence of SCE decreased from 13.6% to 2.5% in Bayomen (P = 0.001), from 8.7% to 6.6% in Ngongol (P = 0.205) and from 6.4% to 5.4% in Nyamongo (P = 0.282). The median age of SCE shifted from 20 (IQR: 12-23) to 29 years (IQR: 18-33; P = 0.018) in Bayomen, from 16 (IQR: 12-21) to 26 years (IQR: 21-39; P < 0.001) in Ngongol and from 16 (IQR: 13-19) to 24 years (IQR: 19-32; P < 0.001) in Nyamongo. The proportions of SCE aged < 10, 10-19, 20-29 and ≥ 30 years shifted from 9.5, 58.3, 25.0 and 7.1% in 1991-1992 to 2.7, 20.5, 39.3 and 37.5% in 2017, respectively.

Conclusions: SCE prevalence decreased overall between 1991-1992 and 2017. The age shift observed is probably due to a decrease in the number of new cases of epilepsy resulting from the dramatic reduction of Onchocerca volvulus transmission after 19 years of CDTI.

Keywords: Cameroon; Community study; Epilepsy; Onchocerciasis.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Map of the study area. Crude prevalence estimates are based on the suspected cases of epilepsy. The map was created CBC by using ArcGIS v.10.3.1. (ESRI 2018). The basemap layer was retrieved from OpenStreetMap and contributors, CC-BY-SA (http://www.openstreetmap.org)
Fig. 2
Fig. 2
Study flowchart. *SCE, suspected case of epilepsy; **PWE, person with epilepsy
Fig. 3
Fig. 3
Variation in crude prevalences of SCE between 1991–1992 (dark grey) and 2017 (light grey). Abbreviations: SCE, suspected case of epilepsy; NS, no significant difference
Fig. 4
Fig. 4
Age shift of the cohort of people living with epilepsy between 1991–1992 and 2017
See this image and copyright information in PMC

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